function unique(arr) {
    let result = [];
    for (let str of arr) {
        if (!result.includes(str)) {
            result.push(str);
        }
    }
    return result;
}

let strings = ["Hare", "Krishna", "Hare", "Krishna", "Krishna", "Krishna", "Hare", "Hare", ":-O"];

alert(unique(strings));